Self-lubricated bearings using polytetrafluoroethylene (PTFE) as a sliding surface have been in use in the aerospace industry since the 1960's according to U.S. Pat. No. 4,666,318 (hereinafter, the 318 patent). The 318 patent teaches that thin films of woven PTFE bearing surfaces are frequently reinforced with sintered bronze and textile yarns such as glass, graphite fibers, or high strength organic yarns of relatively high melting point. Woven structures are usually infused with resin systems such as phenol formaldehyde, epoxies or cyanoacrylates to bind the sliding surface into a dense structure. The 318 patent goes on to teach improved bearings using a reinforced low-friction plastic element consisting of PTFE having a sliding surface and a counterface with a low surface roughness and high hardness.
U.S. Pat. No. 3,996,143 (hereinafter, the 143 patent) describes a bearing surface consisting of a cured mixture of an acrylate composition, a particulate solid lubricant, and organic or inorganic fillers. The bearing surface can be applied by conventional techniques such as spraying, brushing, or dipping. The bearing surface adheres to the substrate and can be built up to any thickness. In addition, the bearing surface conforms easily to the shape of the substrate being coated, can readily be produced in various thicknesses, often can be machined to size, and as such has significant advantage over materials previously employed such as self-lubricating fabrics.
U.S. Pat. No. 4,053,665 teaches a molded bearing assembly with one surface coated by a cured mixture of a curable acrylate composition and particulate PTFE. In addition, U.S. Pat. No. 6,180,574 teaches a self-lubricating liner for bearings which includes a curable acrylate composition and a solid lubricant such as PTFE.
U.S. Patent Application Publication 2009/0275685, teaches a bearing having a surface and a self-lubricating surface coating composition including a curable acrylate composition having a metallic acrylate compound.
These and other works have advanced the self-lubricated bearing field and in particular the use of cured, self-lubricating acrylate surface compositions. These self-lubricating acrylate surface compositions impart the bearing with many desirable processing advantages and are becoming increasingly important. Still there exists a need for improved bearings with conformable and machinable, self-lubricating surfaces for enhanced service life and improved performance.